Proprioception is the awareness of one's own body position. Proprioception enables a person to balance while standing or walking upright. It also enables a person to consciously and unconsciously flex various muscles to strengthen joints and thereby reduce injuries. The role of proprioception in improving athletic performance in preventing joint injuries and in rehabilitation is becoming more recognized as detailed in, for example, “Refining Rehabilitation With Proprioception Training: Expediting Return To Play” by Edward R. Laskowski et al., The Physician and Sportsmedicine, Vol. 25,No. 10.
There are many machines that exercise the lower body. For example, ankle exercisers are disclosed in Lepley et al., U.S. Pat. No. 4,452,447, issued Jun. 5, 1984; Troxel, U.S. Pat. No. 4,605,220, issued Aug. 12, 1986; Stodgell, U.S. Pat. No. 5,368,536, issued Nov. 29, 1994; Bemardson, U.S. Pat. No. 5,851,166, issued Dec. 22, 1998; and Hayden, U.S. Pat. No. 6,277,057, issued Aug. 21, 2001. With these exercisers, the foot is secured on a platform and then moves the platform along a controlled path. None of these exercisers require the user to maintain balance and none of them are useful for assessing and improving proprioception.
A variety of products to improve a user's sense of balance are also known. O.E.M. Medical of Carlsbad, Calif. produces the K.A.T 550 and 3000 machines that feature an inflatable bladder upon which the users stands. Another balancing device is the Wobble Board, a platform mounted upon a downwardly-extending hemispherical member. These products are reactive in the sense that the user controls the movement. Neither of these devices enables the platform to be tilted so that the user is required to respond accordingly.
U.S. Pat. No. 5,755,652 issued May 26, 1998 to Gardner discloses an exercise apparatus having a tilting platform mounted upon two wedge-shaped parts that rotate relative to each other and relative to the platform. Movement from one direction of tilting to another direction requires a clockwise or counterclockwise sweep of the platform. For example, the Gardner machine cannot directly tilt front to back or side to side. Furthermore, rapid changes in tilting are not possible because of the time required for the wedge-shaped parts to rotate. And finally, random movement of the platform requires one of the wedge-shaped parts to be connected to and then rapidly disconnected from the other wedge-shaped part.
Accordingly, there is a demand for an improved machine for assessing and improving a user's proprioception. In particular, there is a demand for an improved machine that tilts a platform upon which a user stands and requires the user to maintain balance upon it.